Case report: Findings in ovaries development from an aborted equine fetus.
Authors: Cuccato Matteo, Bertuglia Andrea, Divari Sara, Brambilla Eleonora, Grieco Valeria, Bollo Enrico, Scaglione Frine Eleonora
Journal: Frontiers in veterinary science
Summary
# Editorial Summary An aborted female foal presented with grossly abnormal ovaries—bilaterally enlarged (6 × 5 cm), pale, and grayish with an unusually robust vascular network—prompted detailed histological and immunohistochemical investigation to establish a definitive diagnosis. Initial microscopic examination suggested a benign hamartoma (tumour-like malformation), characterised by hepatocyte-like polygonal cells arranged in cord-like patterns within lobular structures, but tissue-specific immunomarkers for liver and ovarian tissues excluded this diagnosis entirely. The immunohistochemical analysis revealed that these morphological features represented a unique developmental stage of equine ovarian tissue rather than pathology, demonstrating characteristics distinctly different from both adult horse ovaries and those of other mammalian species. This distinction is clinically important because similar gross and histological presentations in late-gestation equine fetuses might otherwise be misclassified as hamartomas or neoplastic lesions, leading to unnecessary concern during routine post-mortem examinations. Understanding the normal developmental variation in equine fetal ovaries—particularly the dramatic changes in size, vascularisation, and parenchymal organisation—helps practitioners and pathologists differentiate physiological development from genuine pathology, ultimately refining our interpretation of aborted foal necropsies and reproductive failure investigations.
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Practical Takeaways
- •When examining aborted equine fetuses, enlarged ovaries with unusual histological appearance may represent normal developmental variation rather than pathology—immunohistochemistry can confirm diagnosis and avoid overdiagnosis
- •Understanding normal late-stage fetal ovarian development in horses is essential to differentiate physiological changes from true pathological conditions like hamartomas or neoplasia
- •This case demonstrates the importance of comprehensive diagnostic investigation (histology + immunohistochemistry) when unusual ovarian findings are encountered in fetal necropsies
Key Findings
- •Aborted female foal presented with bilaterally enlarged, pale ovaries (6 × 5 cm) containing unusual histological architecture mimicking hepatic tissue with lobular organization
- •Histological examination revealed polygonal cells with abundant cytoplasm arranged in cords with central veins, initially suggesting hamartoma diagnosis
- •Immunohistochemical analysis using tissue-specific markers excluded hamartoma and neoplasia, confirming these findings represent normal late-stage fetal ovarian development in equines
- •Late-stage equine fetal ovaries display unique morphological characteristics distinct from adult horse ovaries and other mammalian species